1. Field of the Invention
The present invention relates to a collision detection device for a vehicle.
2. Background Information
It is already known to use ultrasonic sensors for distance measurement in vehicles. Preferably, the ultrasonic sensors are realized as transceiver units for ultrasonic signals. An ultrasonic signal is sent out by the ultrasonic transceiver unit and is reflected by an obstacle in the surrounding environment of the vehicle. The reflected signal is then received by the ultrasonic transceiver unit. From the propagation time and the speed of sound, a distance of the obstacle from the ultrasonic sensor is determined. Preferably, this measured distance is used to operate a warning device that warns a driver of the vehicle against approaching too close to obstacles. In order to enable the reception of the ultrasonic signals, the ultrasonic transceiver unit has a membrane capable of oscillation on which a piezo-element is situated. In a first operating mode, the piezo-element is used to excite the membrane to oscillation, and thus to send out ultrasonic signals. In addition, oscillations received by the membrane are also transmitted to the piezo-element, so that the oscillations have the result that at the piezo-element a voltage corresponding to the oscillations can be picked off, amplified, and evaluated in order to determine the propagation time of the reflected signal and to obtain the distance value therefrom.
In addition, in vehicles it is known to use acceleration sensors that detect a sudden deceleration of the vehicle. If the vehicle collides with an obstacle and is sharply decelerated by this collision, the resulting deceleration can be detected via the acceleration sensor. Dependent on the detected deceleration, restraint devices in the vehicle can be triggered, for example, a safety belt or an airbag.